Seedling root-dip in phosphorus and biofertilizer added soil slurry method of nutrient management for transplanted rice in acid soil

Abstract

Management of phosphorus (P) in acid soils is becoming more challenging in the anticipated scenario of potential phosphate crisis in agriculture, because the P-use and-recovery efficiencies (PUE and PRE) of existing P management methods are notoriously low in acid soils. This investigation reported a rhizosphere-based P management method for improving P nutrition of rice (Oryza sativa L.) seedlings at the time of transplantation in order to support better root growth on post transplantation. By performing two independent incubation experiments, the critical doses of orthophosphate and incubation duration for seedling root-dip (SRD) in single super phosphate (SSP) amended soil slurry (a sandy clay loam Inceptisol, pH 4.3) were found to be 112.5 mg P kg -1 soil and 10 h, respectively using the critical curve approach. In field experiments, the rhizosphere-based P method (SRD in soil slurry + phosphate solubilizing bacteria, PSB + rock phosphate, RP (30 kg P 2 O 5 ha -1 ) performed better than SSP broadcast as basal application (60 kg P 2 O 5 ha -1 ) in terms of more root volume and P uptake of shoot and root at 45 days after transplantation (DAT), higher P uptake and content in rice grain and straw, enhanced PUE and PRE, comparable grain yield and 50% reduction in P fertilizer input quantity. This rhizosphere based P management (SRD in soil slurry+PSB+RP) method may be vigorously exploited for managing P nutrition in transplanted rice grown in acid soils.